Metasonix D-1000

This is a general help page for certain issues with the D-1000 drum machine. Before using this info, we strongly suggest you read the owner's manual.

Versions
The first production of the D-1000 (100 pcs) had only a clock output from the built-in sequencer. The second revision can be told from the first revision by the marking below the Clock jack. First revisions says "Clock Out", second revision (shown) says "Clock In/Out". Further information is specified in the owner's manual. If use of an external clock is desired, please note that a short pulse is recommended, NOT a square wave. It should be a 0-5 volt signal, like a "TTL signal".

Many "digital logic" Euro modules can make a suitable clock pulse. A good example is the +/- output from the Doepfer A-165 trigger modifier--it converts every pulse from an LFO or other clock signal into two short pulses, one at the rise of the square wave and one at the fall. Innerclock Systems clock interfaces, such as their "Sync-Step," also make suitable pulses.

Adjusting resonance
The D-1000 is quite different from most "classic" drum machines. Like the Boss Dr. Rhythm or Roland TR-606, it makes a drum sound by hitting a bandpass filter with a short pulse rather than an audio signal. The filter is set to resonate at almost, but not quite, the point when it breaks into constant oscillation. It's a very primitive drum machine, and so isn't as user friendly as solid-state drumboxes.

Because tubes age and change with time, the resonance of a D-1000 drum circuit might change, requiring adjustment.

See the procedure in the owner's manual. The knobs for the drum circuit needing adjustment should be set as seen at right. Then, with the D-1000 powered on and the output connected to an amplifier, hold down the ROLL button for that drum sound, and slowly adjust the trimpot for the drum sound (on the bottom of the PC board, shown at below right) until the drum sound is just about to break into constant oscillation. Be careful while doing this--the tubes may be damaged by clumsy handling, and the trimpots are a bit fragile and might be damaged by knocking them around. The trimpots are 20-turn types--if you turn them too far, you will hear a "clicking" sound. Turn the other way until you hear resonance changing, multiple turns will be required.

Note that, if you don't use the CV inputs on the drum circuits, the CV Level knobs may be used as "fine-tuning" controls. They insert a small DC offset, making it easier to tune the drum. Leave the main Tune knob set to approximately the 11-o'clock position, and adjust CV Level instead. This is a "hidden" function.

other
If resonance adjustment doesn't help, and you can't get proper resonance, either the D-1000 circuit is damaged or the tube is getting weak. The tubes in the D-1000 are real, honest, new-old-stock American-made items. They are operated very, very conservatively, and should last for many, many years. In fact, we expect them to last for decades. However, this is impossible to guarantee, and occasionally a tube that tested and worked perfectly may age prematurely, or develop a problem due to physical rough treatment. If you don't have a spare tube, try swapping the tubes in the D-1000 around to see if the problem follows a specific tube. You must have ALL FOUR TUBES installed in the D-1000, because their heaters are connected in a series string. Leave a tube out and the other tubes will not function.

If you don't like the built-in sequencer, use an external pulse sequencer. The MFB SEQ-02 is perfect, it is programmed in a manner similar to the classic Roland drum machines and generates perfect short pulses for the D-1000 circuits. There is a video posted here, showing a SEQ-02 wired to a D-1000--power for the SEQ-02 was "stolen" from the D-1000, so the entire system was fitted into the D-1000 cabinet. (This is an advanced modification, and is NOT recommended for beginners.)

clock input on rev-1 models
'''WARNING: this is NOT a simple mod. If you're not experienced in DIY, do NOT try this yourself. The D-1000 is full of CMOS chips, and if you screw up the soldering or connections you can damage them.'''

On the PC board next to the CLOCK SPEED knob, there are two small pads with a very skinny trace between them. The pad on the LEFT is the clock output of the internal generator, the pad on the RIGHT is the INput for an external clock source.

You need to cut the skinny trace (VERY carefully) and connect the tip of a jack to the RIGHT-hand pad, and connect the sleeve of the jack to the D-1000 ground (around the outer edge of the board). If you use a jack with a built-in switch, wire the LEFT pad to the switch connection of the jack thru a 1k resistor, so the D-1000 will still run without the external clock plugged in.

Again, this is NOT a trivial mod, use extreme caution.

As above, you need to feed the D-1000 a short 0-5 volts clock pulse. Square waves will not work properly.

5v issues
The internal logic of a D-1000 runs on approximately 8.5v DC power. It is derived from the internal +10v power with a dropping resistor and filter capacitor on the extreme left edge of the PC board. Stock D-1000s should accept 0-5v clock pulses from external equipment. However, we have heard of situations where gear that supposedly produces 5v pulses was not clocking a D-1000. If a D-1000 with clock input is not being clocked by an external source, make certain the external clock is actually 0-5 volts---it might not be reaching 5 volts.

We have successfully modified a D-1000 to power an MFB SEQ-02 sequencer. The sequencer triggered the D-1000 drum sounds with no problems, the internal D-1000 clock generator clocked the MFB sequencer with no problems. Video here. This should also work with an MFB sequencer powered from a conventional Euro synth cabinet with +-12 volt power rails.

If a D-1000 clock input is not being operated from an external source, and no other method is available, the solution is to change the 100-ohm resistor to a 7805 regulator chip. Warning: it is also a major modification, and should only be attempted by an experienced technician. It is a "last resort" modification. You should make ABSOLUTELY certain that this is necessary before performing it.